The command line arguments given to the process.
The first element is the command name used to invoke the program.
The following elements are the command-line arguments
given to the program.

val executable_name : string

The name of the file containing the executable currently running.

val file_exists : string -> bool

Test if a file with the given name exists.

val is_directory : string -> bool

Returns true if the given name refers to a directory,
false if it refers to another kind of file.
Raise Sys_error if no file exists with the given name.Since 3.10.0

val remove : string -> unit

Remove the given file name from the file system.

val rename : string -> string -> unit

Rename a file. The first argument is the old name and the
second is the new name. If there is already another file
under the new name, rename may replace it, or raise an
exception, depending on your operating system.

val getenv : string -> string

Return the value associated to a variable in the process
environment. Raise Not_found if the variable is unbound.

val command : string -> int

Execute the given shell command and return its exit code.

val time : unit -> float

Return the processor time, in seconds, used by the program
since the beginning of execution.

val chdir : string -> unit

Change the current working directory of the process.

val getcwd : unit -> string

Return the current working directory of the process.

val readdir : string -> string array

Return the names of all files present in the given directory.
Names denoting the current directory and the parent directory
("." and ".." in Unix) are not returned. Each string in the
result is a file name rather than a complete path. There is no
guarantee that the name strings in the resulting array will appear
in any specific order; they are not, in particular, guaranteed to
appear in alphabetical order.

Set the behavior of the system on receipt of a given signal. The
first argument is the signal number. Return the behavior
previously associated with the signal. If the signal number is
invalid (or not available on your system), an Invalid_argument
exception is raised.

catch_break governs whether interactive interrupt (ctrl-C)
terminates the program or raises the Break exception.
Call catch_break true to enable raising Break,
and catch_break false to let the system
terminate the program on user interrupt.

val ocaml_version : string

ocaml_version is the version of OCaml.
It is a string of the form "major.minor[.patchlevel][+additional-info]",
where major, minor, and patchlevel are integers, and
additional-info is an arbitrary string. The [.patchlevel] and
[+additional-info] parts may be absent.